On a case of polyembryony in Pterocarya fraxinifolia (Juglandaceae) and on polyembryony in general

A case of twin nucelli in an ovule of Pterocarya fraxinifolia, originated from a cleavage of the nucellus primordium and presumably representing a hitherto unrecorded type of polyembryony in Juglandaceae, is discussed. The qualification of this category of polyembryony as “false polyembryony” according to the conventional classification of Ernst is unsatisfactory. A new system of classification of polyembryony is proposed.